AN AIR FRESHENER OR INSECTICIDAL COMPOSITION AND A DEVICE COMPRISING THE SAME

Abstract

The present invention relates to a non-aqueous, single phase, non-thickened liquid air freshener or insecticidal composition having a flashpoint of greater than 62°C comprising: a) a polar solvent; b) up to 10 wt% of a non-polar aliphatic hydrocarbon solvent; and c) a fragrance or insecticide. The invention also provides a device comprising the same.

Full Text

The present invention relates to air freshener or insecticidal compositions, particularly those which can be evaporated from a container through a wall such as a membrane.
Air freshener and insecticidal compositions are well-known. These are used to fragrance or deodorize an environment or to control insects. Such compositions have traditionally been in solid form, but now may be in liquid, including thickened liquid or gelled, form. The liquid is generally held in a chamber.
The chamber may have a wicking arrangement such that the composition is evaporated from a wall which is in the form of a porous surface. Alternatively, the chamber may have at least one wall of a material that is permeable to the vapours of the composition, thereby allowing controlled release of the vapours over a period of time. Such an arrangement' is described in US-A-4,534,509, in which the fragrance is enclosed in an impermeable bag with a weak seal along one edge, which prevents escape of the vapours as long as the package is sealed. This is then contained within a larger pouch of a suitable permeable membrane. When sufficient pressure is applied by the user, the weak seal ruptures and the volatile composition flows from the inner pouch into the outer permeable pouch, thereby allowing release of the vapours. An alternative arrangement is described in US-A-4,634,614 in which the permeable wall is covered with a thin layer of paper coated with a polymer sheet to which adheres a protective sheet which is impermeable to the vapours of the composition. The paper layer tears when subjected to a peeling force such that the protective layer is readily removed and the volatile substance is covered only by a layer of material which is permeable to the vapours, thereby allowing release of the vapours. A similar

arrangement is described in WO 98/23304 which comprises a membrane laminate having a plurality of layers. The outer layers of the laminate are impermeable to the composition and its vapours, and thus prevent escape of the vapours as long as the package is sealed. Upon opening, delamination occurs at the interface between two selected layers of the laminate such that the composition ,is covered only by a layer of the material which is permeable to the vapours of the composition.
In such devices. ever constraints are placed on the composition contained within the chamber. In particular it met be able to evaporate satisfactorily through the wall relatively constantly throughout the life of the device. the device must also be storable for a long time without the composition affecting the properties of the wall or other parts of the chamber. Furthermore the rate of evaporation of the composition must be controllable by the manufacturer such that a suitable life time of the device can be provided, which is generally of the order of 45 days. It is desirable that after, approximately, this period a suitable end of life indicator is provided. This is so that the consumer can see when it is appropriate to buy a new device or refill composition for such a device. Suitable indication means are, for example, a significant visible reduction in the amount of the composition in the device, a change in colour of the composition, or a change in form of the composition, for example from a liquid to a non-flowing gel.
In prior art devices of the type in which a composition is always in contact with the wall of a chamber and evaporates out of the chamber through said wall, there is a relatively small amount, for example, around 3g, of the composition present. In order to provide effective fragrance for a life time of around 4 5 days, the composition must have a high

concentration of fragrance with consequently only a small amount of solvent present. The solvent is chosen such as to aid diffusion of the fragrance through the wall of the chamber. A non-polar solvent is generally used since such a solvent has good diffusion properties through such walls.
It is now desired to produce such devices which may contain a greater quantity of liquid composition since some consumers regard this as beneficial. In order to obtain appropriate fragrancing or insecticidal properties under ambient conditions (i.e. at room temperature), it is not possible simply to increase the amount of composition present because this will increase the life time of the device. This may not be desirable when a life time of about 4 5 days is required. Furthermore relatively constant fragrancing throughout the life time of device may not be achievable. Additionally, and more importantly, using a larger amount of the composition in the chamber will increase the amount of non-polar solvent present in the chamber. It has been found that such a quantity of non-polar solvent is sufficient to damage the wall during storage or use of the device, which will mean that the device will not function properly once it is opened or has been used for a short time. For example, if the wall is of the laminated membrane type, the membrane may suffer delamination.
It is not possible simply to replace the non-polar solvent with a polar solvent. Polar solvents are known to have poorer evaporation characteristics through membranes, and in particular will not normally pass through membrane walls of the type used in air freshener or insecticidal devices.
It is also desirable that a suitable end-of-life indication be provided for devices of this type so that the consumer can see when it is appropriate to

buy a new device or refill composition for such a device. Suitable indication means include the visible absence of any composition in the device. Thus it is particularly desirable for the composition to be formulated such that no residue of the solvent remains. The end-of-life indication is then simply when all of the solvent of the composition has disappeared, i.e. has evaporated out of the device.
We have surprisingly discovered a composition which can be used in larger quantities in an air freshener or insecticidal device which has the appropriate evaporation characteristics through a wall membrane and which does not destroy or damage the wall during storage or use of the device.
Accordingly the present invention provides a non¬aqueous, single phase, non-thickened liquid air freshener or insecticidal composition having a flash point of greater than 62**C comprising:
a) a polar solvent;
b) up to 10 wt% of a non-polar aliphatic hydrocarbon solvent; and
c) a fragrance or insecticide.
It has surprisingly been found that by using a mixture of a particular polar solvent and a particular non-polar solvent, the evaporation characteristics of the composition can easily be controlled by the manufacturer by altering the relative proportions of the two components and by an appropriate choice of each component. In particular in the present invention the amount of non-polar solvent in the composition is not too high. Thus the membrane wall is not damaged or destroyed.
It is known that the polar solvent by itself does not easily pass through the permeable membrane walls of the types used in air fresheners and insecticide

devices and therefore does not provide adequate evaporation characteristics. It has surprisingly been found that when it is used in conjunction with the non-polar solvent, the polar solvent will have appropriate characteristics to dissolve and evaporate with the fragrance or insectiC1de and will not damage or destroy the membrane wall. Therefore using a combination of a polar solvent and a non-polar solvent will provide the composition with appropriate characteristics for use in an air freshening or insectiC1dal device having a wall through which the composition diffuses.
The polar solvent may be chosen•from a wide range of solvents, such as glycol ethers. Desirably the glycol ether is a (C1_4 alkyl) glycol (C1_4 alkyl) ether, di(C1-4 alkyl) glycol (C1_4 alkyl) ether, (C1_4 alkyl)glycol di (C1-4 alkyl) ether, di{C1-4 alkyl) glycol di (C1-4 alkyl) ether or tri(C1-4 alkyl) glycol (C1_4 alkyl) ether. The alkyl groups may have 1, 2, 3 or 4 carbon atoms and may be, for example, methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, s-butyl or t-butyl groups.
For example, the polar solvent may be 3-butoxypropan-2-0I sold under then trade mark Dowanol PnB, propylene glycol monomethyl ether sold under the trade mark Dowanol PM, tripropylene glycol methyl ether sold under the trade mark Dowanol TPM, dipropylene glycol methyl ether sold under the trade mark Dowanol DPM, dipropylene glycol dimethyl ether sold under the trade mark Proglyde DMM, dipropylene glycol n-propyl ether sold under the trade mark Dowanol DPnP, dipropylene glycol mono n-butyl ether sold under the trade mark Dowanol DPnB, tripropylene glycol mono n-butyl ether sold under the trade mark Dowanol TPnB or propylene glycol n-butyl ether.
A single polar solvent, or a mixture of two or more polar solvents, may be used.

The non-polar aliphatic hydrocarbon solvent may also be chosen from a wide variety of such solvents. Examples are linear, cyclic or branched hydrocarbons. Preferred hydrocarbons are linear or branched alkanes such as C9-18 alkanes, for example C9-16 alkanes, espeC1ally C9-12 alkanes or C11-15 alkanes. A single non-polar solvent, or a mixture of two or more non-polar solvents, may be used. Often, however/ a mixture of hydrocarbons is used since it is not necessary to use a single hydrocarbon and separation of different hydrocarbons is costly.
Preferred non-polar solvents are mixtures of C9-12 and C11-15 alkanes such as those sold under the trade marks Isopar G, Isopar H, lisbpar J, Isopar K, Isopar M, Isopar M, Isopar L and Isopar MB, as well as mixtures of C13-16 alkanes such as those sold under the trade mark Isopar P, and distillates sold under the trade mark Isopar V. Other preferred non-polar solvents are aliphatic hydrocarbons sold under the trade marks Norpar 12 and Norpar 15, and cycloparaffinic hydrocarbons sold under the trade marks Exxsol D60, Exxsol D80, Exxsol DlOO, Exxsol D220, Exxsol D230, Exxsol DlOOs, Exxsol DUO, Exxsol D120 and Exxsol D140.
The composition has a flash point of greater than 62°C, preferably greater than 70°C. This is to ensure that the composition is not a fire hazard in use. Individual components of the composition may have flash points of less than these temperatures, so long as the final composition meets this requirement. Desirably the flash pint of each component is as high as possible. We have found a correlation between the flash point of a compound and its rate of evaporation relative to n-butyl acetate. Evaporation rates can be expressed on a scale in which n-butyl acetate has an evaporation rate of 100, A higher value means that the compound has a greater rate of evaporation, and a

lower flash point. In general the evaporation rate of the polar solvent is preferably less than 100. The evaporation rate of the non-polar aliphatic hydrocarbon solvent is preferably less than 16.
The composition desirably comprises at least 15 wt% of the polar solvent, for example from 15 to 40 wt%, espeC1ally 15 to 30 wt% of the polar solvent based on the total weight of the composition. The composition comprises less than 10 wt% of the non-polar aliphatic hydrocarbon solvent, for example from 1 to 10 wt%, preferably 3 to 8 wt%, espeC1ally 4 to 7 wt%, based on the total weight of the composition. The weight ratio of the polar solvent to the non-polar solvent is desirably from 1:1 to 6;1, preferably from 2:1 to 5:1, more preferably from 3:1 to 4:1. The amounts of each component and the weight ratio are, of course, chosen to provide a composition with appropriate characteristics.
The composition also comprises a fragrance when it is to be an air freshener composition, or an insectiC1de when it is to be an insectiC1dal composition. Air freshener fragrances are well-known to those skilled in the art. Any air freshener fragrance or fragrance composition compatible with the membrane can be used. Some fragrance compositions also contain a polar or non-polar solvent falling within the definitions set out above, or compounds which have an air freshening or deodorising effect but which also act as such a solvent. Any such solvent or compounds in the fragrance composition which is added to the final composition is to be taken into account when calculating how much polar solvent or non-polar solvent is present in the final composition. In particular it is important for the total content of non-polar aliphatic hydrocarbon solvent in the composition to be less than 10 wt%. Any suitable

insectiC1de can be used.
The fragrance is desirably present in an amount of from 50 to 80 wt% of the total composition, for example from 60 to 75 wt%.
The composition may also comprise one or more optional components which are conventionally used in the art, such as a dye or ultra-violet absorbing agent such as dihydroxybenzophenone to stabilize the fragrance or dye if necessary.
The amount of composition which can be contained in the device is not limited. However, since the composition is compatible with membrane wall, a larger amount of composition can be held in the device than has previously been feasible. For example, 5g to 50g of composition can be used, preferably 5g to 20g, more preferably about 8 to lOg.
The present invention also provides an air freshener or insectiC1dal device which comprises a chamber containing a composition as defined above, said chamber having at least one wall of a material which enables the vapours of the composition to diffuse into the environment in which, the device is placed.
The wall is permeable such that it allows the fragrance or insectiC1de to diffuse into the environment. It may be made of any suitable material, for example polyethylene or paper. The wall may have another layer laminated to either or both surfaces thereof, for example a layer or layers made of a polymer such as polyethylene. The wall may, in particular, be that described in US-A-4,634,614. Alternatively the wall may be that described in WO 98/23304. In the latter document there is described a wall in the form of a permeable polyethylene membrane. The wall preferably is thin so as to allow a suitable

release rate of the composition. For example the wall may have a thickness of 20 to 100 micrometers, preferably 30 to 70 micrometers, espeC1ally 40 to 60 micrometers.
In order to prevent the device from releasing fragrance or insectiC1de before it is used, said wall may be covered by an impermeable sheet which is removed before the device is used. For example, the sheet may simply be peeled off the wall or otherwise removed and discarded. The sheet may be made of, for example, a laminate such as polyethylene laminated with a metal such as aluminium.'In WO 98/23304 the impermeable sheet is a laminate of polyethylene and ethylene-vinyl alcohol copolymer. Alternatively a number of vents may be provided to allow for an adjustable release of the fragrance or insectiC1de.
The following Examples further illustrate the present invention.

EXAMPLE 1
Compositions consisting of single polar or non-polar solvents or comprising a polar solvent and a non-polar solvent were tested in an air freshener device to determine their weight loss through a membrane over time.
The solvents chosen were as follows:
Non-Polar Solvents

Isopar M,

a mixture of C1j_i5 isp-alkanes obtainable from Exxon having a flashpoint of 79'C and an evaporation rate of

Isopar L,

a mixture of C1x-is iso-alkanes obtainable from Exxon having a flashpoint of 67"C and an evaporation rate of 3.

3. Isopar P,

a mixture of C13-i6 iso-alkanes obtainable from Exxon having a flashpoint of 109°C and an evaporation rate of

Norpar 12,

a mixture of aliphatic hydrocarbons derived from petroleum obtainable from Exxon having a flashpoint of >66'*C and an evaporation rate of 1.

5. Exxsol D60,

a mixture of aliphatic cycloparaffinic hydrocarbons obtainable from Exxon having a flashpoint of eS^C and an evaporation rate of 2.5.

6. Exxsol D80,

a mixture of aliphatic

cycloparaffinic hydrocarbons obtainable from Exxon
having a flashpoint of 75°C and an evaporation rate of
Polar Solvents
A. Dowanol PnB/ 3-butoxypropan-2-ol obtainable
from Dow Chemicals having a flashpoint of SB^C and an evaporation rate of 7.
B. Dowanol PM, propylene glycol monomethyl ether
obtainable from Dow Chemicals having a flashpoint of 31 "C and an evaporation rate of 70.
C. Dowanol DPM, dipropylene glycol methyl ether
obtainable from Dow Chemicals having a flashpoint of 75°C and an evaporation rate of 3.
D. Proglyde DMM, dipropylene glycol dimethyl ether
obtainable from Dow Chemicals having a flashpoint of GS'C and an evaporation rate of 80.
The above evaporation rates are relative to n-butylacetate having an evaporation rate of 100; the figure for Proglyde DMM was calculated as the molecular weight x vapour pressure (mm Hg at lO'C). A high flashpoint generally gives a low evaporation rate.
The above solvents were used singly or combined in weight ratios of 75:25, 50:50 and 25:75. 8g of each of the compositions was sealed in thermoformed reservoirs having a membrane laminate of linear low density polyethylene and aluminium as described in WO 98/23304 on one side thereof. The devices were

activated by peeling back the aluminium laminate layer
to expose the membrane. The devices were stored at
ambient conditions and the weight loss monitored over
15 days.
The following table sets out the weight loss percentages over time:

It can be seen that the weight loss can be controlled by choosing appropriate solvents and by choosing appropriate ratios of the two solvents.
EXaMPLB 2
A composition containing a fragrance was prepared to provide a composition for use in a membrane/liquid reservoir system having a fill weight of 9g.
Exxsol D60 6%
Proglyde DMM 24%
C1trus fragrance 68%
2,4-dihydroxybenzophenone 2%
{u.v. absorber)
The fragrance contained some polar solvent, namely 0.3% dipropylene glycol, 9.2% butoxypropanol and 0.9%

triethyl C1trate. The composition was sealed in the same device as used in Example 1, except that the membrane thickness was reduced from 60 micrometers to 40 micrometers.

WE CLAIM:
1. A non-aqueous, single phase, non-thickened liquid air freshener or insecticidal
composition having a flashpoint of greater than 62°C comprising:
a) a polar solvent;
b) up to 10 wt% of a non-polar aliphatic hydrocarbon solvent; and
c) a fragrance or insecticide.

2. The composition according to claim 1 which is an air freshener composition and which comprises a fragrance.
3. The composition according to claim 1 or 2 in which the polar solvent has an evaporation rate of less than 100 and the non-polar solvent has an evaporation rate of less than 16, based on a scale in which n-butyl acetate has an evaporation rate of 100.
4. The composition according to any one of the preceding claims wherein the polar solvent is a glycol ether.
5. The composition according to claim 4 wherein the polar solvent is a (C1-4 alkyl) glycol (C1-4 alkyl) ether, di (C1-4 alkyl) glycol (C1-4 alkyl) ether, (C1-4 alkyl) glycol di (C1-4 alkyl) ether, di (C1-4 alkyl) glycol di (C1-4 alkyl) ether or tri(t1-4 alkyl)glycol (C1-4 alkyl) ether.
6. The composition according to claim 4 wherein the polar solvent is 3-butoxypropan-2-ol, propylene glycol monomethyl ether, tripropylene glycol methyl ether, dipropylene glycol methyl ether, dipropylene glycol dimethyl ether, dipropylene glycol n-propyl ether, dipropylene glycol mono n-butyl ether, tripropylene glycol mono n-butyl ether or propylene glycol n-butyl ether.

7. The composition according to any one of the preceding claims wherein the non-
polar solvent is a C10-18 alkane or cycloparaffmic hydrocarbon.
8. The composition according to any one of the preceding claims in which the weight ratio of the polar solvent to the non-polar solvent is from 1:1 to 6:1.
9. The composition according to claim 8 wherein the ratio is from 2:1 to 5:1.
10. An air freshener or insecticidal device which comprises a chamber containing a
composition as defined in any one of the preceding claims, said chamber having at
least one wall of a material which enables the vapours of the composition to diffuse
into the environment in which the device is placed, preferably the wall is made of a
polyethylene and optionally has a thickness of from 20 to 100 micrometers.
11. The device according to claim 10 wherein the wall is made of a polyethylene.
12. The device according to claim 10 or 11 wherein the wall has a thickness of from 20 to 100 micrometers.